http_api_util 0.1.2

use std::{collections::{VecDeque, HashMap}, hash::Hash};
pub trait ApiCache<K, V> 
where K: Hash + Eq
{
    fn get(&self, request: &K) -> Option<&V>;
    fn put(&mut self, request: K, response: V);
    fn capacity(&self) -> usize;
    fn clear(&mut self);
    fn new(capacity: usize) -> Self;
}


pub struct FifoCache<K, V> {
    queue: VecDeque<K>,
    index: HashMap<K, V>,
    capacity: usize
}

impl<K, V> ApiCache<K, V> for FifoCache<K, V> 
where K: Hash + Eq + Clone
{
    fn get(&self, request: &K) -> Option<&V> {
        self.index.get(request)
    }

    fn put(&mut self, request: K, response: V) {
        if self.queue.len() == self.capacity {
            if let Some(_) = self.queue.pop_front() {
                self.index.remove(&request);
            };
        }
        self.queue.push_back(request.clone());
        self.index.insert(request, response);

    }

    fn capacity(&self) -> usize {
        self.capacity
    }

    fn clear(&mut self) {
        self.queue.clear();
        self.index.clear();
    }

    fn new(capacity: usize) -> Self {
        Self {
            queue: VecDeque::with_capacity(capacity),
            index: HashMap::with_capacity(capacity),
            capacity,
        }
    }
}